Electrical devices permeate almost every aspect of modern society. Continued advancements in circuit integration has made possible numerous consumer products that were, for the most part, unimaginable even a few years ago.
Yet irrespective of complexity, electronic circuitry continues to require the supply of electrical power, usually in the form of source voltage in order to operate properly. At a basic level, the source voltage originates from an external source, either from an alternating current (AC) line voltage that is transformed and rectified, or a direct current (DC) voltage source device such as a battery pack.
Common source voltages used in electronic devices, such as computers and computer peripheral devices such as disc drives, include nominal voltage levels such as +5.0 volts or +3.3 volts. It is important to ensure that the source voltage or voltages supplied to electronic circuitry remain within specified tolerances to ensure proper operation of (and prevent damage to) the electronic circuitry. Voltage regulators have thus for many years been incorporated into the electronic circuitry of electronic devices to provide regulation of the source voltages to desired levels.
With increases in device complexity, system designers have increasingly employed voltage margin testing as a way to evaluate the robustness of new circuit designs. By adjusting the magnitude of the source voltage, the effects of various environmental conditions likely to be encountered by the device during normal consumer use can be evaluated. Moreover, some devices have been designed with some level of programmability so that, depending upon the requirements of a given application, an optimum magnitude of source voltage can be selected for use by the circuitry. Such adjustable voltage regulators are discussed, for example, by U.S. Pat. No. 5,770,939 and U.S. Pat. No. 5,774,734.
While operable, these and other devices fail to support real-time programmability and level detection, especially for circuits that are integrated into a single device. That is, while external voltage source levels supplied to the device can be readily adjusted up or down to simulate a range of real world voltage supply conditions, and the circuitry adjacent discrete voltage regulators can be manually manipulated to provide different voltage regulator outputs, at present there is no easy way to efficiently perform voltage margin testing in an integrated circuit device that internally incorporates voltage regulation circuitry.